Blood Test May Reduce Stigma of Depression

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Can a psychiatric disorder be diagnosed with a blood test? That
may be the future if two recent studies pan out. Researchers are
figuring out how to differentiate the blood of a depressed person
from that of someone without depression.

In the latest study, published today (April 17) in the journal
Translational Psychiatry, researchers identified 11 new markers,
or chemicals in the blood, for early-onset depression. These
markers were found in different levels in
teens with depression compared with their levels in teens who
didn't have the condition.

Currently, depression is diagnosed by a subjective test,
dependent upon a person's own explanation of their symptoms, and
a psychiatrist's interpretation of them. These blood tests aren't
meant to replace a psychiatrist, but could make the diagnosis
process easier.

If a worried parent could have a family physician run a blood
test, it might ease the diagnosis process during the already
tough time of adolescence, said Eva Redei, a professor at
Northwestern University in Evanston, Ill., who was involved in
the study of the teen-depression blood test.

If they hold up to further testing, blood tests could help young
adults, who often go untreated because they aren't aware of their
disease, get treated. The biological basis of a blood test could
also help to reduce that stigma, researchers suggest. [ 10
Facts About the Teen Brain ]

Depressing diagnosis

In the new study, Redei and her colleagues focused on early-onset
depression, which occurs in teens and young adults before age 25.
About 15 percent of young women and 7 percent of young men
between ages 13 and 18 are estimated to have the disease.

This disease is a distinct condition, different from adult-onset
depression, she said. In teens, "it has a somewhat greater
genetic contribution, and also it has usually a harder
course," Redei told LiveScience.

The researchers first looked at the genes of rats that had been
bred to be either more or less depressed, considered the "genetic
model." Next, they looked at four different strains of rats
placed under chronic stress, an environmental factor that causes
depression. They compared the gene-expression changes, which can
occur as a result of stress, between the
chronically stressed rats and individuals without extra
stress.

The researchers then took 26 gene-expression changes they'd
identified in the animals to see if they held up in depressed
humans; they tested 14 depressed and 14 non-depressed teens.
Eleven of the genetic markers faithfully distinguished between
teens with and without
depression.

Building to a blood test

In an earlier study, published in the Feb. 28 issue of the
journal Molecular Psychiatry, researchers focused on a blood test
for adult-onset depression. The researchers used nine markers,
consisting of proteins and other body chemicals that had
previously been identified as related to depression and brain
functioning.

With these markers, they came up with a formula to give each
patient's blood test a score, which indicated the likelihood of
having depression.

The researchers analyzed the blood of 70 depressed adults and 43
non-depressed controls. The average score of the depressed
patients was 85, and the score of the non-depressed patients was
33. The researchers said the test could detect depression in 90
percent of people who actually have the condition.

"We expect that the biological basis of this test may provide
patients with insight into their depression as a treatable
disease rather than a source of self-doubt and stigma," John
Bilello, chief scientific officer of Ridge Diagnostics, which
makes the blood test and sponsored the study, said in a
statement.

"Only about 25 percent of depressed teens are being treated," she
said. "It has to do with the fact that they have to go through
this process to be diagnosed, and then there is a stigma attached
to it."

Because a blood test provides physical evidence of a disease, it
could help counter misconceptions about depression, such as that
it is all in a person's head, or is a sign of some personal
weakness, the reasoning goes.

"It will help remove that stigma, if we have something you can
attach a number to," Redei said."Eventually the whole society
will accept that this disease, depression, isn't something you
can just get over by pulling yourself up."